The Great Saint Martin Church (Groß Sankt Martin) foundations (circa 960 AD) rest on remnants of a Roman chapel, built on what was then an island in the Rhine. The church was later transformed into a Benedictine monastery.
In 1150, a fire destroyed much of Cologne and it is supposed that the entire church was destroyed. The Archbishop of Cologne Philipp I. von Heinsberg sanctified the new building in 1172, and the first phase of construction, the tri-apsidal structure was built, with three round apses meeting in the shape of a cross. This is the only element of the church still present today. The eastern end of the nave was completed before a further fire in 1185, as well as aisles on the Southside. At the northern apse, two Benedictine chapels were later added, built over the ruins of the previous abbey buildings.
In the middle of the 13th century, new walls for the three apses were completed, with larger windows. These provided a sought-after lightness to the interior. The nave was also made five meters longer, and the atrium in the west was built.
After the completion of the church in the 13th century, few modifications to the form of the church were undertaken. Most significant during this period were the various renovations needed for the four surrounding towers.
Reforms under abbots Jakob von Wachendorp (1439–1454) and Adam Meyer (1454–1499) provided a stronger financial footing for the Benedictine abbey. From this the inner decoration of the church was embellished, including figures from the altar, installed in 1509, that are still present today.
In 1707, the decaying interior walls were repaired and refurbished. Heinrich Obladen, then the abbot of Great Saint Martin, also purchased a new, larger organ for the church. New adornments for the Church took on a Baroque style, including golden bands for the pillars, dome and walls.
The church was badly damaged in World War II; restoration work was completed in 1985.
References:Visby Cathedral (also known as St. Mary’s Church) is the only survived medieval church in Visby. It was originally built for German merchants and inaugurated in 1225. Around the year 1350 the church was enlarged and converted into a basilica. The two-storey magazine was also added then above the nave as a warehouse for merchants.
Following the Reformation, the church was transformed into a parish church for the town of Visby. All other churches were abandoned. Shortly after the Reformation, in 1572, Gotland was made into its own Diocese, and the church designated its cathedral.
There is not much left of the original interior. The font is made of local red marble in the 13th century. The pulpit was made in Lübeck in 1684. There are 400 graves under the church floor.